1. Field of the Invention
The present invention relates to a compressing apparatus of refrigerant gas for a reciprocating compressor and particularly, to a gas suction apparatus for a reciprocating compressor capable of improving compressing performance of refrigerant gas and reliability of components.
2. Description of the Background Art
Generally, a compressor is an instrument for compressing fluid such as air and refrigerant gas. The compressor generally includes a driving unit installed in a closed container, for generating a driving force and a compressing unit for sucking and compressing refrigerant gas by receiving the driving force of the above driving unit and is classified into a rotary compressor, reciprocating compressor and a scroll compressor according to the structure of the compressing unit.
The reciprocating compressor among them is a compressor in which a driving force of the driving unit is transmitted to the piston and the piston sucks and compresses refrigerant gas performing linear reciprocating movement in a cylinder.
FIGS. 1 and 2 show an embodiment of the compressing unit of the reciprocating compressor and the compressing unit of the reciprocating compressor includes a cylinder 10 where a through hole 11 forming a compression space P inside the hole is formed, a piston inserted in the through hole 11 of the cylinder 10 enabling linear reciprocating movement and a discharge valve assembly 30 combined to the end portion of the cylinder 10 to cover the through hole 11.
The piston 20 has a head portion 22 at one side of the body portion 21 having a certain length and a connection portion 23 extended into a certain area at the other side of the body portion 21. In the body portion 21, a first gas passage 24 having a certain depth is formed in the body portion 21 and in the head portion, a second gas passage 25 is formed.
The first gas passage 24 is composed of a hole and the second gas passage 25 is composed of a plurality of through holes.
A suction valve 40 for opening and closing the second gas passage 25 is positioned in the head portion 22 and the connection portion 23 of the piston 20 is connected into the driving unit for generating a driving force.
On the other hand, the suction valve 40 is composed of a thin plate in a round form and has a dissection portion 41 is positioned inside the valve. The suction valve is divided into a fixing portion 42 and opening and closing portion 43 by the dissection portion 41.
The suction valve 40 is fixed-combined to the head portion 22 having a fixing bolt 50 penetrated by the fixing portion 42 under the condition that the valve is contacted on the end surface of the head portion 23 of the piston 20.
Also, the discharge valve assembly 30 includes a discharge cover 31 combined to cover the end portion of the cylinder 10, a discharge valve 30 inserted in the discharge cover 31, for opening and closing the compression space P formed by the through hole 11 and piston 20 of the cylinder 10 and a valve spring 33 for elastically supporting the discharge valve 32.
In the operation of the compressing unit of the above reciprocating compressor, first, a driving force of the driving unit is transmitted to the piston 20 and the piston 20 performs linear reciprocating movement in the cylinder 10.
In the process, as shown in FIG. 3, when the piston 20 moves to the direction of a bottom dead point a, the discharge valve 32 is contacted on the end portion of the cylinder 10 by pressure difference and blocks the compression space P. At the same time, the suction valve 40 combined to the piston 20 is bent and open the second gas passage 25, thus to suck refrigerant gas to the compression space P formed in the cylinder 10 through the first gas passage 24 and the second gas passage 25 of the piston 20.
When the piston 20 moves to an upper dead center (b) after reaching the bottom dead center (a), the suction valve 40 is restored to the former condition and the second gas passage 25 of the piston 20 is closed, thus to compress refrigerant gas sucked to the compression space P formed in the cylinder 10. When the piston 20 reaches the top dead center (b), the discharge valve 32 is opened and the compressed refrigerant gas is discharged.
As the above process is repeated continuously, refrigerant gas is compressed.
However, in the above structure, since the suction valve 40 formed as a thin plate is fixed-combined by the fixing bolt 50, the head portion of the fixing bolt 50 is positioned in the compression space P in the protruded form and accordingly, a dead volume is generated, thus to decline compressing efficiency. Also, position sensing of the top dead center (b) and bottom dead center (a) of the piston 20 is difficult and accordingly, controlling of a stroke of reciprocating movement of the piston 20 becomes difficult.
Since the suction valve 40 formed as a thin plate is combined by the fixing bolt 50, design of the second gas passage 25 is limited. Namely, in case the flowing cross section of the second gas passage 25 is large, the flowing cross section where the refrigerant gas flows becomes large. However, the suction valve 40 formed as a thin plate could be damaged by an excessive suction pressure in bending the valve and in case the size of the flowing cross section of the second gas passage 25 is small, the flowing resistance of refrigerant gas could be increased by the small cross section.
As the piston 20 moves, in the process that the suction valve 40 is repeated opened or closed, a slip rotation is generated between the suction valve 40 and the fixing bolt 50 and accordingly, compressing performance could not be performed well since the piston 20 is seceded from the second gas passage 25.
Also, as the suction valve 40 was bent and restored to its former state, the second gas passage 25 is opened or closed and accordingly, a fatigue crack is generated and a screw hole 44 for combining the fixing bolt 50 is formed at the bending portion of the suction valve 40. Therefore, structural strength was declined.
As a structure for making up for the above disadvantage, as shown in FIG. 4, an embodiment that the fixing portion 42 of the suction valve 40 is directly welded-connected to the end surface of the head portion 22 of the piston 20 is disclosed.
With such structure, the dead volume can be reduced and control of a stroke is eased but, characteristic of the material is changed by heat transformation by welding heat for welding the suction valve 40 on the head portion 22 of the piston 20. When the opening and closing operation of the suction valve 40 is continuously performed, cracks by fatigue are generated centering around the welding point, thus to decrease reliability of the compressor.
Therefore, the present invention provides a gas suction apparatus for a reciprocating compressor which can make the suction of refrigerant gas smoothly and increase structural combining strength.
Also, another object is to provide a gas suction apparatus for a reciprocating compressor which can minimize dead volume of a compression space of refrigerant gas and ease controlling of a stroke.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a gas suction apparatus for a reciprocating compressor comprising a piston having a gas flowing passage where refrigerant gas flows, being inserted in the compression space formed in a cylinder enabling linear reciprocating movement, a fixing means combined to the piston, an inertia valve including a valve cone portion formed to have a larger area than the cross section of the gas flowing passage and a certain thickness, for opening and closing the gas flowing passage, being contacted on the end surface of the piston or separated, a valve body portion extended having a smaller outer diameter than the inner diameter of the gas flowing passage at the center of the one side surface of the valve cone portion and inserted in the gas flowing passage, a plurality of guide members extended to have a certain length on the outer circumferential surface of the valve body portion and contacted on the inner circumferential surface of the gas flowing passage and an inertia valve penetrated-formed to have a certain width and length in the valve body portion having the fixing means inserted in the valve.
The foregoing and other, features, aspects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.